Re: [PATCH] x86: don't rely on VMWare emulating PAT MSR correctly

[H. Peter Anvin]

On 12/16/2014 01:58 AM, Juergen Gross wrote:
> VMWare seems not to emulate the PAT MSR correctly: reaeding
> MSR_IA32_CR_PAT returns 0 even after writing another value to it.
> 
> Detect this bug and don't use the read value if it is 0.
> 
> Commit bd809af16e3ab1f8d55b3e2928c47c67e2a865d2 ("x86: Enable PAT to
> use cache mode translation tables") triggers this VMWare bug when the
> kernel is booted as a VMWare guest.
> 
> Reported-by: Jongman Heo <jongman.heo@xxxxxxxxxxx>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> Tested-by: Jongman Heo <jongman.heo@xxxxxxxxxxx>

I presume cachability control is irrelevant for a VMware guest?  I'm
wondering if it would be better to just plain ignore the failure rather
than disabling PAT.

	-hpa


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